After many months of being like Oh man I gotta do that, my friend recently dug up the copy of Awful Green Things From Outer Space that he first played as a child--originally printed in Dragon Magazine in 1979 and with the chits originally glued to little pieces of linoleum or something by some 12 year old of his acquaintance back in the day.
To be quick:
1. It rules.
2. It is highly D&Dable.
So the basics are this:
-There's a ship (above)
-There's little counters for Player One: Crew members with what a gamer will recognize as different Move, Attack and Health stats who can move around the ship.
-There's little counters for weapons they can pick up (pool cues, knives, stun guns, cans of rocket fuel, etc) which have different characteristics.
-There's little counters for Player Two: Aliens who invade the ship starting in a random location. The aliens start as eggs, then become babies, then become adults--all 3 stages with different stats.
-They fight.
If you are familiar with the Warhammer family of games, you may recognize all these elements from the Warhammer 40k-derived game Space Hulk, where one side plays Genestealers (Alien alien knock-offs) and one side place Terminators (big guys in oversized extra-cool space marine armor).
Space Hulk replaces chits with miniatures (cool improvement) and replaces the map-ripped-from-Dragon-Magazine with a board full of cardboard tunnels you can make yourself (cool improvement), however, unless Space Hulk has been upgraded since I've played it lacks the one super-cool thing that makes Awful Green Things really special and replayable:
Weapons are scattered all over the ship when the aliens invade--and each one has one of a variety of totally random effects. Everything from a blaster to an electric fence can do one of about a dozen things and you don't know which until you use it on an alien.
Some do a ton of damage, some do almost none, some shrink the aliens, some grow the aliens, some make the aliens burst into tiny fragments which then grow--it's scary using weapons but you will lose if you don't experiment with them. It makes for a new experience every time.
There's later editions and an expansion game for Green Things--I don't know if they added "randomly teleports you to another room" or "turns out the lights in the corridor no-one can see" to the weapon effects, but they should.